code: def sending_headers(self):
      print("Sending trace ID:", TraceContext.current_trace_id())
      return {
          "x-tracing-id": TraceContext.current_trace_id(),
      }
  
imports: import argparse
  import sys
  import threading
  import uuid
  import pyarrow
  import pyarrow.flight
label_desc: Use image node_id 1 for calling the TracingClientMiddleware obj's underlying member method code with example usage: obj.sending_headers() and returns: dict